Replaceable hinge type abrasive units or packs for cylindrical hub structures

ABSTRACT

The pack unit comprises a flap-like member of fill material and a mounting member distinct from the flap-like member for mounting the latter on one of the circumferentially spaced mounting pins of a rotary wheel hub structure, with the pack unit extending radially outwardly of the axis of the hub structure. The mounting member is a relatively rigid unitary one prior to association with the flap-like member and is preferably cut in the desired length from an elongated extrusion made, as an example, from an aluminum or a rigid plastic composition. The mounting member provides a single radially inner and axially extending portion formed with an opening of one of several shapes which telescopes axially onto one of the mounting pins. The mounting member includes a pair of integral, radially outer and outwardly extending arm formations on the inner portion and co-extensive therewith in overall length. The radially inner portion of the flap-like member is located between and is secured to the arm formations by staples or other fastening elements which clamp the arm formations against the fill material therebetween. A circumferential series of pack units may be mounted for pivotal movement on the pins of the hub structure and may be readily removable therefrom for replacement upon expected wear by the separation of component parts of the hub structure.

United States Patent [191 Belanger June 28, 1974 REPLACEABLE HINGE TYPE ABRASIVE UNITS OR PACKS FOR CYLINDRICAL HUB STRUCTURES Related US. Application Data [63] Continuation of Ser. No. 155,733, June 23, 1971,

abandoned.

[52] US. Cl. 51/334 [51] Int. Cl B24b 9/02 [58] Field of Search 51/334-337, 51/394, 401-407 56] References Cited UNlTED STATES PATENTS 2,597,421 5/1952 White 51/334 3,645,049 2/1972 Freerks 51/334 3,653,856 4/1972 Field 51/334 3,711,261 l/l973 Burns 51/334 Primary Examiner-Othell M. Simpson Attorney, Agent,.0r Firm-Whittemore, Hulbert & Belknap [57] ABSTRACT The pack unit comprises a flap-like member of fill material and a mounting member distinct from the flaplike member for mounting the latter on one of the circumferentially spaced mounting pins of a rotary wheel hub structure, with the pack unit extending radially outwardly of the axis of the hub structure. The mounting member is a relatively rigid unitary one prior to association with the flap-like member and is preferably cut in the desired length from an elongated extrusion made, as an example, from an aluminum or a rigid plastic composition. The mounting member provides a single radially inner and axially extending portion formed with an opening of one of several shapes which telescopes axially onto one of the mounting pins. The mounting member includes a pair of integral, radially outer and outwardly extending arm formations on the inner portion and co-extensive therewith in overall length. The radially inner portion of the flap-like member is located between and is secured to the arm formations by staples or other fastening elements which clamp the arm formations against the till material therebetween. A circumferential series of pack units may be mounted for pivotal movement on the pins of the hub structure and may be readily removable therefrom for replacement upon expected wear by the separation of component parts of the hub structure.

25 Claims, 8 Drawing Figures PAIENTEBJUH28 1914 3.820.291

SHEEI 1 BF 2 33 INVENTOR 39 J/mfs A. AZZ/IA/6ZIG ATTORNEYS CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation of application Ser. No. 155,733, filed June 23, 1971, now abandoned.

My co-pending application, Ser. No. 885,734, filed Dec. 17, 1969, now U.S. Pat. No. 3,685,217 of Aug. 22, 1972, shows and describes a rotary finishing wheel or tool, in which a cylindrical hub structure is, in certain illustrated embodiments, generally similar to the hub structure of the present invention, although not of a type characterized by separable disc or flange parts; and the abrasive she'et pads or packs shown and described in that application, although pivotally mounted on certain hub-carried pins, are individually of a nature very different from those herein shown, described and claimed.

Another of my co-pending applications, Ser. No. 857,885, filed Sept. 15, 1969, now U.S. Pat. No. 3,626,646 of Dec. 14, 1971, relates to abrasive sheet packs pivoted on pins of a solid section hub structure by means of a separate unitary retainer device having portions which loop or partially wrap around axially spaced portions of a pivot pin.

My later co-pending application, Ser. No. 156,008, filed June 23, 1971, now U.S. Pat. No. 3,772,833 of Nov. 20, 1973, discloses another version'of an axially separable confining flange or end plate-type hub structure adapted for the use of abrasive units generally similar to those herein disclosed, also a simple hand-tool for facilitating the separation of the end plates or flanges of the hub structure for assembly and, if needed, replacement of worn units..

BACKGROUND OF THE INVENTION 1. Field of the Invention The replaceably hinged flexible pad-like abrasive units or packs of the present invention find application, preferably but not necessarily in association with a cylindrical hub structure of the nature herein disclosed, in various types of buffing wheels, polishing wheels, non-solid type grinding wheels, and other related applications for the rough or finish abrasive working, brushing, burnishing or polishing of metal or other rigid parts.

2. Description of the Prior Art Abrasive pack-type units of a nature and use only generally similar to those disclosed herein are the sub jects matter of prior U.S. Pats. to Block, No. 2,804,730 of Sept. 3, 1957; Peterson, No. 2,984,053 of May 16, 1961; Block, No. 3,058,269 of Oct. 16, 1962, and Burns, No. 3,533,198 of Oct. 13, 1970. However, they all lack disclosure of structural features and functional attributes such as are referred to in the above abstract and will be hereinafter described in detail.

My own U.S. Pats. No. 3,455,068 of July 15, 1969, and 3,535,833 of Oct. 27, I970, respectively bearing co-pending parent and divisional application status, also relate to rotary finishing tool structure.

SUMMARY-OF THE INVENTION The improved wheel of the invention comprises a cylindrical hub structure of a very simple but rugged nature capable of being inexpensively mass-produced in the main of stamped parts. It is inexpensively assembled both in regard to the hub components and the application of the abrasive packs to the hub, and affords a fast and easy dismantling of the hub for removal and replacement of any one or all of the abrasive packs. The latter, as pivotally mounted on individual transverse pins spanning the axial space between end flange members of the hub structure, one of which members is removable from the hub for access to the pack, are also capable of inexpensive massproduction. I-lub mounting parts for the packs are in the form of sections of extruded aluminum or plastic stock sawed transversely to afford individual identical, relatively rigid mounting members. These members are provided with cylindrical through-holes or quasi-cylindrical reentrant key-hole type through-openings, either of which type removably telescope axially with reasonable clearance on the transverse pivot pins of the hub for a hinged pack connection which also restrains the pack and its mount against undesirable radial movement relative to the hub structure under high speed operation and vibration.

The extruded-type mounting sections also present integral stop portions against which radially inner ends of the respective assembled sheet packs may be abutted, thus insuring an outer circumferential surface continuity of the abrasive structure as a whole.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary axial end view, as in the direction of the arrow of FIG. 2, of a typical abrasive finishing wheel constituted in multiple by one version of the improved replaceable abrasive pack and by the improved cylindrical hub structure of the invention;

FIG. 2 is a fragmentary view in generally horizontal cross section on broken line 2-2 of FIG. 1;

FIG. 3 is a fragmentary end view in enlarged scale of a replaceable pad-like abrasive sheet pack and its extruded metal mounting member, in accordance with the embodiment of the invention also illustrated in FIGS. 1 and 2;

FIG. 4 is a fragmentary view similar to FIG. 3 of an alternative embodiment presenting an uninterrupted cylindrical pivot and retainer hole in the body of the mounting member;

FIG. 5 illustrates another optional modification, similar to that of FIG. 4 save for the fact that the abrasive unit may incorporate two or more similar packs clamped by the mounting extrusion, being separated from one another by a central rib portion of said extrusion;

FIG. 6 is a fragmentary axial end view, generally similar to FIGS. 4 and 5, of still another modification of the abrasive sub-assembly, in which pack-clamping arm projections of the mounting member are shown as radi ally restraining a loop-type abrasive pad or pack unit, an alternative pivot hole arrangement being indicated in dot-dash line;

FIG. 7 is a fragmentary side elevational view of an adaptation of the sheet pack assembly for use on a hub structure of the type disclosed in my co-pending application, Ser. No. 885,734, now U.S. Pat. No. 3,685,217, identified above; and

FIG. 8 is another embodiment of the same type as,

and for the same purpose as the embodiment of FIG. 7.

DESCRIPTION OF PREFERRED EMBODIMENTS FIGS. 1 and 2 of the drawings illustrate a typical abrasive work finishing wheel or rotary tool, generally designated by the reference numeral 10, which is made up in general of an axially central and radially flanged tubular driving hub unit or structure 12, and a multiplicity of identical replaceable abrasive sheet pack units 14, pivotally mounted to the hub structure 12 in equal circumferential spacing about the latter. The number may, of course, vary, but in general and by preference the circumferential array of the abrasive units 14 is such as to afford a substantially continuous circumferential wheel surface characteristic at the outer extremities of the abrasive packs 14.

As shown in FIGS. 1 and 2, the cylindrical hub structure 12, which is contemplated for preferred use in as sociation with any of the abrasive pack forms dealt with herein, comprises an axially inner sleeve component 15 made up of an inner tubular member 16 and a radially outwardly extending flange member 17 fixedly mounted concentrically or coaxially-upon one axial end of said sleeve. The latter may be in the form of a onepiece stamping of a suitably thick gauge sheet metal, of which the disc-like flange portion 17 is an integral part; or, in the alternative the sleeve unit 15 may comprise an inner cylindrical sleeve part' 16 to an end of which a separate disc or flange component in the form of a separate annulus of appropriate inner and outer diameter is welded in a flush relation; A separate inverted cup-like, -internal bearing part 18, preferably a sheet metal stamping, is snugly telescoped into the bore of sleeve part 16, preferably with a forced fit insuring a fixed relationship of element 18 to the sleeve unit 15. The member 18 presents an integral, radially outwardly extending annular stop flange 19 overlapping the sleeve disc or flange part 17; and an axial outward flanging of member 18 at 20 presents a bore at which the sleeve component 15 is to be drivingly engaged with a power shaft or the like (not shown).

Sleeve unit 15 is completed by a second and removable annular flange or disc element 22 whose circular central bore is sized to telescope with relatively free vclearance over the axial end of sleeve 16 opposite the flanged end 17 f the latter. The outer end of sleeve element I6 is chamfered to enable an easy application of the disc 22 thereto.

At points on diametrically opposite sides of the sleeve unit its permanent flange 17 is shown as having a pair of hex-headed nuts 23 secured fixedly thereto, as by welding; or, in the alternative, theflange may be drilled and tapped. In either case, the purpose is to threadedly receive the end of a machine bolt or stud 24, whose hex-head 25 bears against the outer end axial surface of removable flange disc 22. This holds the latter in a conflningengagement with the side of the abrasive sheet pack 14, later to be described in detail, but with insufficient axial end pressure on the latter in the direction of flange 17 to prevent a free pivotal action of the individual pack units 17 contemplated by the invention.

A pivotal axis for each of the abrasive units 14is provided by a pin 26 extending axially through the space between disc or flange components 17,-22 of the hub sleeve sub-assembly 15. These pins, as uniformly distributed about and adjacent the periphery of the cylindrical hub structure 12 (one for each pack unit 14), are

fixedly mounted on sleeve flange 17, as by welding the pins at 27 (FIG. 2) in holes in said flange 17, the pins extending through the transverse space between flanges l7 and 22 and parallel to the axis of the wheel, i.e., at to the flanges. The ends of the pins 26 opposite their welded anchor connections are chamfered for ready reception in a similar number of similarly distributed holes 28 in the removable flange 22.

Thus, the flange 22, as mounted at its series of holes I 28 in a telescoped relation to both the hub sleeve part 16 and the pivot pins 26, as shown in FIG. 2, and secured in this relationship by the bolts or studs 24, completes a cylindrical hub structure 12 which is dually flanged to receive the abrasive packs 14. The structure is of a very rugged nature, and is obviously very simply and inexpensively constituted as to its parts. When it is desired to remove and replace one or more of the packs 14, this is accomplished easily and with a minimum of wheel down time by simply removing the two bolts 24, taking off the flange disc 22, lifting out the abrasive pack or packs to be replaced, and restoring and clamping the disc to its operative position over the reconstituted group. i

The embodiment of pack unit 14 shown in FIGS. 1, 2 and 3 is, as indicated above, in the form of a stack of identical individual abrasive or equivalent type finishing sheets 30, allof a radially elongated rectangular shape. They may be of any suitable fill material indicated for the purpose, such as abrasive coated, emerytype cloth or fabric, leather, sisal and the like, and may be specially treated, if required, in a manner known to the art. Likewise, radially inner ends of the sheets may be bonded together, as by an appropriate mastic, to impart a rigid, block-like characteristic to those ends.

Each of the pack units 14, in the embodiment of FIG. 3, is pivotally mounted to wheel hub structure 12 by a single rugged unitary sheet mounting and pivoting part 32 which is individual to, and a second component of, the pack unit 14. By preference, each such part 32 is in the form of a transversely sawed rigid section of an elongated extrusion of aluminum, for example, or other extrudable or plastically pre-moldable material, such as any one of a number of synthetic plastics. Such section 32 is continuous and uninterrupted in its axial length, which equals that of the stack illustrated in FIG. 2, so that it and the pack assembly or unit as a whole are axially confined quite closely at opposite sides thereof by hub flanges l7 and 22, yet are free to pivot individually in action relative to hub structure 12.

More specifically in reference to FIG. 3, the clamping member 32 is of a generally forked outline in cross section in a plane normal to its pivotal axis. It presents a pair of stack clamping arms or furcations 33 which generally parallel one another, although being slightly divergent in an original free, uncompressed position of the arms 33, such as is indicated in dotted line in FIG. 3. Arms 33 merge integrally into a somewhat block-like radially inner body portion 34 of the member 32 at which it pivotally mounts the pack unit 14 to the hub assembly 12 of wheel 10, more particularly, to an individual transverse pivot pin 26 of hub sleeve member 15, as depicted in FIGS. 1 and 2.

For this purpose, the body 34 of each pack-clamping and pivoting member 32 is formed to provide an opening, generally designated 35, which may be described as being key-hole shaped. That is, the opening comprises a radially inner portion 36 of quasi-cylindrical outline, in excess of 180 and less than 360 extent, so as to present re-entrant projections at 37 which wrap radially outwardly around the pivoting pin 26, the radius of the hole portion 36 only slightly exceeding that of the pin. Thus, the pivoting and clamping member 32 may be freely telescoped axially onto the end of a pin 26 in initial assembly and subsequent replacement operations. The re-entrant key-hole nature of opening 35 prevents significant radial shift of the pad unit 14 in relation to hub structure 12, notwithstanding a relatively free fit on the pin, and imparts a degree of flexibility to member 32 in regard to its clamp arms 33.

Relatively wide mouth portions 38 of the openings 35 radially outwardly of the projections 37 are shaped to afford substantially 90 shoulder surfaces 39, which are radially inwardly abutted by the end of the stack of sheets 30, thus positively and accurately positioning the latter for a uniform continuous outer circumference of the wheel 10. With the sheets so positioned between the arms or furcations 33, the latter are clamped strongly against the stack by heavy duty U-shaped staples 40, as driven through the arms 30 with the staple prongs clinched tightly against the outer surface of one of the arms. For a pack unit 14 of the limited axial extent appearing in FIG. 2, one such staple will usually suffice; for greater axial widths a plurality of staples will be required; and it is to be understood that rivets or other types of rigid locking means are contemplated for the purpose.

Two alternative types of unitary, plastically premoldable stack mounting member are illustrated in FIGS. 4 and 5 of the drawings, both characterized by a fully cylindrical pivot hole, as distinguished from the wraparound keyhole type hole characteristic of FIG. 3. To the extent that certain features of the packs clamping and pivoting body member, as specially designated 42 in FIG. 4, correspond with features common to the corresponding body member 32 of FIG. 3, they are designated by corresponding reference numerals, primed, and further description thereof is dispensed with. Similarly corresponding features appearing in FIG. 5, as well as to some extent in FIG. 6, are designated by corresponding reference numerals, again or double primed.

Thus, a single pack abutment surface 43 of the pack unit 42 of FIG. 4 is substituted for the stop shoulders 39 of FIG. 3 in view of the fact that the units pivot hole 44 is fully cylindrical in this case. Relief slots 45 are formed between the ends of surface 43 and the clamp arms 33, thus imparting a desired measure of increased flexibility to those arms in clamping the stacked sheets 30.

As illustrated in FIG. 5, the packs pivoting and clamping construction is similar to that of FIG. 4, the body thereof being generally designated 46. In this case, two or more like but separate stacks of sheets 30 are clamped between outer fork arms or furcations 33'. of a set of three or more such arms; and an axially inner arm 48 of the same thickness and radius separates the pack sheet components, affording a backing for clamping force exerted by the staple means 40' on arms 33". The stacks radially inwardly abut stop surfaces 49 between the arms.

A further optional embodiment of the pack unit which is shown in FIG. 6 and is specially designated 50 differs in one respect from those previously described in that the abrasive sheet component 51 thereof is constituted by sheets superposed in a stack and folded upon themselves in a looped fashion about a transverse shaping and restraining pin 52 in the bight of the loop, the loop received in a laterally enlarged space between parallel clamp arms or furcations 53 of the pre-molded pivotal mounting body, here generally designated 54.

Each of the arms 53 is formed on its inner surface to provide a nose projection 55, and when the arms are drawn together in clamping by the staple means 40", their noses 55 take against zones of the sheets just radially outwardly of the restricted neck of the loop bight of the pack. The arms 53 thus of themselves strongly restrain the abrasive pack or pad 51 against radial movement, centrifugal or otherwise, in relation to the stack clamping and pivoting member 54.

The latter is shown in FIG. 6 as being provided with a key-hole shaped pivoting opening 57, similar to the embodiment of FIG. 3. It is also provided with stop shoulders 58 in the event it should be desired to mount a plain stack of abrasive sheets (as in FIGS. 3, 4 and 5 in lieu of the looped type. As a further alternative, the pivotal opening may be in the form of a fully true cylindrical hole, as indicated in dot-dash line in FIG. 6 and designated 59.

FIG. 7 illustrated an adaptation of the composite pack structure of the invention for use on a hub structure having a pair of opposed end plates and an alternative plate spaced axially between the same, the general nature of which is illustrated and described in my copending application, Ser. No. 885,734, now US. Pat. No. 3,685,217, to which reference may be made; and for the purpose of simplicity, such plate means are not shown, although it is contemplated that features of removability as described above may be incorporated.

Thus FIG. 7, illustrated a pack unit or assembly for this purpose, as generally designated by the reference numeral 60, to comprise an extruded pivotal mounting body 61, to which the superposed sheets of an abrasive pack 62 are secured by staple means 63, in the manner described above. The extrusion is centrally apertured at 64, mid-way of its length, to provide a rectangular notch adapted to telescope radially inwardly over an intermediate plate or flange component (not shown) of the hub of the unit, end plates or flanges of the latter being, of course, disposed at opposite ends of the part 61.

In the embodiment of FIG. 8 the structure is basically the same, hence corresponding numerals are employed, save for the fact that the assembly 66 of that figure is relatively more elongated in nature, hence is provided with a requisite number of notches, specially designated 64 is equally spaced relation to one another along its axial length.

What is claimed is:

I. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a mounting member distinct from said flaplike member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit of the hub structure, and at least two integral, radially outerand outwardly extending arm formations on said inner portion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap like member, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm formations against said radially inner portion of said flap-like member and placing the latter under compression, said shape of said inner portion of said mounting member including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, restricted portion of the outline.

2. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a work piece, and a mounting member distinct from said flaplike member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with'said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap-like memher, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm-formations against said radially innner portion of said flap-like member and placing the latter under compression, said shape of said inner portion of said mounting member including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of a fully cylindrical outline adapted to telescope a mounting pin of the hub structure.

3. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a mounting member distinct from said flaplike member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner por' tion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap-like-member, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm formations against said radially inner portion of said flap-like member and placing the latter under compression, the junction of said arm formations with said inner portion of said mounting member being defined by an abutment surface engageable with the inner end surface of said flap-like member, said abutment surface providing a stop for limiting the insertion of the latter into said mounting member.

4. A pack unit adapted to be pivotally mounted on a rotary wheel hub structure having an axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a member distinct from said flap-like member for thus mounting the latter pivotally on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and'axially extending portion which is apertured axially for the pivotal mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion coextensive therewith in overall axial length, between which formations a radially inner portion of said flaplike member is fixedly secured, the pivotal aperturing of the inner portion of said mounting member having a key-hole outline adapted to telescope a mounting pin of the wheel at an enlarged, radially inner portion of the outline and to wrap radially outwardly and reentrantly about such pin at a radially inner, restricted portion of the outline.

5. The pack unit defined in claim 4 in which the juncture of said arm formations with said inner portion of said mounting member is defined by a pair of abutment surfaces engageable with the inner end surface of said flap-like member, said abutment surfaces providing a stop for limiting the insertion of the latter into said mounting member.

6. The pack unit defined in claim 4, in which said mounting member is continuous and uninterrupted throughout the axial length thereof, including said apertured inner portion and its integral arm" formations.

7. The pack unit defined in claim 4 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof.

8. The pack unit defined in claim 4 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof, said apertured inner portion being provided with one or more notches for mounting the pack unit on the hub structure.

9. The pack unit defined in claim 4 in which said inner portion and said arm formations of the mounting member are in the form of a relatively rigid transverse section of an extrusion of metallic or non-metallic stock.

10. The pack unit defined in claim 4 in which said arm formations of said mounting member and said flap- 11. The pack unit defined in claim 4 in which said arm formations of said mounting member and said flaplike member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member and place the latter under compression.

12. The pack unit defined in claim 4 in which the oppositely facing inner surfaces of said am formations are provided with laterally extending projections which engage and compress the radially inner portion of said flap-like member.

13. A pack unit adapted to be pivotally mounted on a rotary wheel hub structure having an axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a member distinct from said flap-like member for thus mounting the latter pivotally on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion which is apertured axially for the pivotal mounting of said pack unit on the hub structure,

and at least two integral, radially outer and outwardly extending arm formations on said inner portion coextensive therewith in overall axial length, between which formations a radially inner portion of said flap-like member is fixedly secured, the pivotal aperturing of the inner portion of said mounting member having a fully cylindrical outline adapted to telescope a mounting pin of the hub structure.

14. The pack unit defined in claim 13 in which the juncture of said arm formations with said inner portion of said mounting member is defined by an abutment surface engageable with the inner end surface of said flap-like member, said abutment surface providing a stop for limiting the insertion of the latter into'said mounting member.

15. The pack unit defined in claim 13 in which said mounting member is continuous and uninterrupted throughout the axial length thereof, including said apertured inner portion and its integral arm formations.

16. The pack unit defined in claim 13 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof.

17. The pack unit defined in claim 13 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof, said apertured inner portion being provided with one or more notches for mounting the pack unit on the hub structure.

18. The pack unit defined in claim 13 in which said inner portion and said arm formations of the mounting member are in the form of a relatively rigid transverse section of an extrusion of metallic or non-metallic stock.

19. The pack unit defined in claim 15 in which said arm formations of said mounting member and said flaplike member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member.

20. The pack unit defined in claim 15 in which said arm formations of said mounting member and said flaplike member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member and place the latter under compression.

21. The pack unit defined in claim 15 in which there is a further arm formation integral with said inner portion, said fill material being divided into a pair of stacks, with each stack being separated by said further arm formation.

22. The pack unit defined in claim 15 in which the oppositely facing inner surfaces of said arm formations are provided with laterally extending projections which engage and compress the radially inner portion of said flap-like member.

23. The pack unit defined in claim 3, in which said shape of said inner portion of said mounting member includes an axial aperture which is of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, restricted portion of the outline.

24. The pack unit defined in claim 3, in which said shape of said inner portion of said mounting member includes an axial aperture which is of fully cylindrical outline adapted to telescope a mounting pin of the hub structure.

25. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer finishing portion adapted to engage a workpiece, and a mounting member distinct from said flap-like member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross-section for the mounting of said pack unit on the hub structure, and a radially outer and outwardly extending portion integral with said inner portion and coextensive therewith in overall axial length, to which outwardly extending portion a radially inner portion of said flap-like member is fixedly secured, the shape of said inner portion including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, re-

stricted portion of the outline. 

1. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a mounting member distinct from said flap-like member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit of the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap-like member, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm formations against said radially inner portion of said flap-like member and placing the latter under compression, said shape of said inner portion of said mounting member including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and reentrantly about such pin at a radially inner, restricted portion of the outline.
 2. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a mounting member distinct from said flap-like member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said Flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap-like member, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm formations against said radially innner portion of said flap-like member and placing the latter under compression, said shape of said inner portion of said mounting member including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of a fully cylindrical outline adapted to telescope a mounting pin of the hub structure.
 3. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis, with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a mounting member distinct from said flap-like member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross section for the mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion and coextensive therewith in overall axial length, said arm formations being laterally movable toward one another upon association with said flap-like member, said flap-like member having a radially inner portion located between said arm formations, and fastening means penetrating said arm formations and said radially inner portions of said flap-like member to urge said arm formations toward one another thereby clamping said arm formations against said radially inner portion of said flap-like member and placing the latter under compression, the junction of said arm formations with said inner portion of said mounting member being defined by an abutment surface engageable with the inner end surface of said flap-like member, said abutment surface providing a stop for limiting the insertion of the latter into said mounting member.
 4. A pack unit adapted to be pivotally mounted on a rotary wheel hub structure having an axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a member distinct from said flap-like member for thus mounting the latter pivotally on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion which is apertured axially for the pivotal mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion co-extensive therewith in overall axial length, between which formations a radially inner portion of said flap-like member is fixedly secured, the pivotal aperturing of the inner portion of said mounting member having a key-hole outline adapted to telescope a mounting pin of the wheel at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, restricted portion of the outline.
 5. The pack unit defined in claim 4 in which the juncture of said arm formations with said inner portion of said mounting member is defined by a pair of abutment surfaces engageable with the inner end surface of said flap-like member, said abutment surfaces providing a stop for limiting the insertion of the latter into said mounting member.
 6. The pack unit defined in claim 4, in which said mounting member is continuous and uninterrupted throughout the axial length thereof, including said apertured inner portion and its integral arm formations.
 7. The pack unit defined in claim 4 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof.
 8. The pack unit defined in claim 4 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof, said apertured inner portion being provided with one or more notches for mounting the pack unit on the hub structure.
 9. The pack unit defined in claim 4 in which said inner portion and said arm formations of the mounting member are in the form of a relatively rigid transverse section of an extrusion of metallic or non-metallic stock.
 10. The pack unit defined in claim 4 in which said arm formations of said mounting member and said flap-like member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member.
 11. The pack unit defined in claim 4 in which said arm formations of said mounting member and said flap-like member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member and place the latter under compression.
 12. The pack unit defined in claim 4 in which the oppositely facing inner surfaces of said arm formations are provided with laterally extending projections which engage and compress the radially inner portion of said flap-like member.
 13. A pack unit adapted to be pivotally mounted on a rotary wheel hub structure having an axis, said pack unit comprising a flap-like member of fill material presenting a radially outer portion adapted to engage a workpiece, and a member distinct from said flap-like member for thus mounting the latter pivotally on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion which is apertured axially for the pivotal mounting of said pack unit on the hub structure, and at least two integral, radially outer and outwardly extending arm formations on said inner portion coextensive therewith in overall axial length, between which formations a radially inner portion of said flap-like member is fixedly secured, the pivotal aperturing of the inner portion of said mounting member having a fully cylindrical outline adapted to telescope a mounting pin of the hub structure.
 14. The pack unit defined in claim 13 in which the juncture of said arm formations with said inner portion of said mounting member is defined by an abutment surface engageable with the inner end surface of said flap-like member, said abutment surface providing a stop for limiting the insertion of the latter into said mounting member.
 15. The pack unit defined in claim 13 in which said mounting member is continuous and uninterrupted throughout the axial length thereof, including said apertured inner portion and its integral arm formations.
 16. The pack unit defined in claim 13 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof.
 17. The pack unit defined in claim 13 in which said integral arm formations are each continuous and uninterrupted throughout the axial length thereof, said apertured inner portion being provided with one or more notches for mounting the pack unit on the hub structure.
 18. The pack unit defined in claim 13 in which said inner portion and said arm formations of the mounting member are in the form of a relatively rigid transverse section of an extrusion of metallic or non-metallic stock.
 19. The pacK unit defined in claim 15 in which said arm formations of said mounting member and said flap-like member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member.
 20. The pack unit defined in claim 15 in which said arm formations of said mounting member and said flap-like member of fill material therebetween have means penetrating the same to clamp said arm formations against said flap-like member and place the latter under compression.
 21. The pack unit defined in claim 15 in which there is a further arm formation integral with said inner portion, said fill material being divided into a pair of stacks, with each stack being separated by said further arm formation.
 22. The pack unit defined in claim 15 in which the oppositely facing inner surfaces of said arm formations are provided with laterally extending projections which engage and compress the radially inner portion of said flap-like member.
 23. The pack unit defined in claim 3, in which said shape of said inner portion of said mounting member includes an axial aperture which is of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, restricted portion of the outline.
 24. The pack unit defined in claim 3, in which said shape of said inner portion of said mounting member includes an axial aperture which is of fully cylindrical outline adapted to telescope a mounting pin of the hub structure.
 25. A pack unit adapted to be mounted on a rotary wheel hub structure having an axis with said unit extending radially outward of the axis, said pack unit comprising a flap-like member of fill material presenting a radially outer finishing portion adapted to engage a workpiece, and a mounting member distinct from said flap-like member for thus mounting the latter on the hub structure, said mounting member being a relatively rigid unitary one prior to association with said flap-like member and providing a single radially inner and axially extending portion of a shape in transverse cross-section for the mounting of said pack unit on the hub structure, and a radially outer and outwardly extending portion integral with said inner portion and coextensive therewith in overall axial length, to which outwardly extending portion a radially inner portion of said flap-like member is fixedly secured, the shape of said inner portion including an axial aperture of at least part cylindrical outline adapted to telescope a mounting pin of the hub structure, said axial aperture being of key-hole outline adapted to telescope a mounting pin of the hub structure at an enlarged, radially inner portion of the outline and to wrap radially outwardly and re-entrantly about such pin at a radially inner, restricted portion of the outline. 